The human spine is a three-dimensional complex structure and so are the problems associated with it. Researchers have directed their efforts, both clinically and biomechanically to understand the behavior of the normal and abnormal spine. Our basic hypothesis is that the whole lumbar vertebral column behaves differently than an isolated motion segment. Our second hypothesis is that degeneration and/or injury and subsequent stabilization of the intevertebral join affects the motion behavior of the neighboring joints. These abnormalities ultimately lead to some malfunction and/or pain. Although the biomechanical response (or behavior) of the various spinal components, such as vertebrae, discs, facets, etc., have been investigated, the response of ligaments to normal and changed motion patterns is not very clear. The present In Vitro study proposes to investigate in situ strains in the normal, degenerated, injured and stabilized specimen subjected to clinically relevant loads. Specifically, we propose to study the biomechanical behavior of spinal ligaments after 3 clinical procedures: (a) disc prolapse; (b) ligamentous injury; and (c) laminectomy and stabilization at one level, e.g., L4-L5 or L3-L4. For this purpose the three-dimensional motion (load-displacement) behavior of each vertebra of the lumbar spinal segment (L1-S1) would be obtained through the stereophotogrammertric technique. The points of insertion of ligaments (morphology) would be determined through a specially designed digitizer (morphometer). The principles of rigid body kinematies would be utilized to combine the load-displacement data and morphological data to yield in situ ligamentous strains. It is anticipated that this proposal will result in more knowledge and a better understanding of the relationship between injury, degeneration and stabilization of the spine and its motion pattern. Any changes in the motion behavior would alter the strains in ligaments. The latter aspect may induce biomechanical changes leading to malfunction. This proposal would also provide basic data concerning ligamentous strains. Since ligaments contain nociceptors, this knowledge may be useful in low back pain research.